title: Factors affecting lactate and malate utilization by Selenomonas ruminantium.
abstract: Lactate utilization by Selenomonas ruminantium is stimulated in the presence of malate. Because little information is available describing lactate-plus-malate utilization by this organism, the objective of this study was to evaluate factors affecting utilization of these two organic acids by two strains of S. ruminantium. When S. ruminantium HD4 and H18 were grown in batch culture on DL-lactate and DL-malate, both strains coutilized both organic acids for the initial 20 to 24 h of incubation and acetate, propionate, and succinate accumulated. However, when malate and succinate concentrations reached 7 mM, malate utilization ceased, and with strain H18, there was a complete cessation of DL-lactate utilization. Malate utilization by both strains was also inhibited in the presence of glucose. S. ruminantium HD4 was unable to grow on 6 mM DL-lactate at extracellular pH 5.5 in continuous culture (dilution rate, 0.05 h-1) and washed out of the culture vessel. Addition of 8 mM DL-malate to the medium prevented washout on 6 mM DL-lactate at pH 5.5 and resulted in succinate accumulation. Addition of malate also increased bacterial protein, acetate, and propionate concentrations in continuous culture. These results suggest that 8 mM DL-malate enhances the ability of strain HD4 to grow on 6 mM DL-lactate at extracellular pH 5.5.
authors.affiliation: Department of Animal and Dairy Science, The University of Georgia, Athens 30602-2771, USA. scottm@uga.cc.uga.edu
authors.forename: J D
authors.initials: JD
authors.lastname: Evans
authors.forename: S A
authors.initials: SA
authors.lastname: Martin
mesh_terms: D000818:Animals; D001431:Bacteriological Techniques; D002417:Cattle; D003470:Culture Media; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006089:Gram-Negative Anaerobic Bacteria / Q000254:growth & development / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism*; D008293:Malates / Q000378:metabolism*; D008297:Male; D012417:Rumen / Q000382:microbiology*; D013045:Species Specificity; D019802:Succinic Acid / Q000378:metabolism
chemical_list: D003470:Culture Media; D008293:Malates; D019344:Lactic Acid; C030298:malic acid; D019802:Succinic Acid; D005947:Glucose